HISTOLOGICAL OBSERVATIONS ON THE REPRODUCTIVE TRACT OF THE EWE By B. J. RESTALL* [Manuscript received November 15, 1965] Summary

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1 HISTOLOGICAL OBSERVATIONS ON THE REPRODUCTIVE TRACT OF THE EWE By B. J. RESTALL* [Manuscript received November 15, 1965] Summary An histological examination of the female reproductive tract showed that all parts of the tract undergo cyclical changes. In general the height of the lumenal epithelium reaches a maximum during oestrus and secretory activity also appears to be maximal at this time. Secretory cells were not seen in the vagina. The cervix, however, had an epithelium continually containing mucus-secreting cells. This mucus was released into the cervical lumen during pro-oestrus and oestrus. The glands of the uterus exhibited secretory activity during pro-oestrus, but it is not clear whether the lumenal epithelium has any secretory function. The fallopian tubes showed evidence of continual secretion, concentrated mainly in the ampulla region. As well, the degree of mucosal folding increased greatly from the isthmic region to the ampulla region. 1. INTRODUOTION The histological changes occurring in the female reproductive tract have been studied in many species (Snyder 1923; Novak and Everett 1928; Grant 1934; Roark and Herman 1950; Hadek 1955). In the sheep, reports of cyclical changes in the intact female reproductive tract are scant and some disagreement exists as to the nature of the changes and their time relationship to the oestrous cycle (Casida and McKenzie 1932; Grant 1934; Cole and Miller 1935; Hadek 1955, 1958). Before undertaking further studies of the female reproductive tract it was deemed necessary to investigate the cyclical changes occurring in the breed of sheep to be studied, namely the Merino. At the same time it was thought desirable to express these changes in a quantitative manner, a task not undertaken before in this species. II. MATERIALS AND METHODS (a) Animals Thirty-seven mature Merino ewes of similar origin were used. (b) Treatment A large flock of ewes were run with raddled, vasectomized rams overnight, and the raddled ewes were discarded. The flock was reteased for the next 22 hr and 37 raddled ewes were obtained for study. These 37 ewes were run with raddled, teaser * School of Wool Technology, University of New South Wales; present address: Department of Veterinary Physiology, University of Sydney. Aust. J. Biol_ Sci., 1966,19,673-86

2 674 B. J. RESTALL rams continuously for the remainder of the trial period. Two ewes were slaughtered at each of the following time intervals after first being marked (day of marking is day 1): 1,2,3,4,5,6,8,10,12,14,15,16,17,18,19,20,21 days. It was noted if the ewes were remarked before slaughter. TABLE 1 CLASSIFICATION OF REPRODUCTIVE TRACTS INTO STAGE OF OESTRUS Ewe No. Days Corpora Lutea No. of after Developing Estimated Initial Follicles Detection Age* >Smmin Oestrus of Oestrus No. (days) Diameter Pro oestrus Pro-oestrus Pro-oestrus Pro-oestrus Oestrus 617 1St 1 >1 Oestrus 61S 1St Oestrus Metoestrus Metoestrus 62S Metoestrus Metoestrus Metoestrus Metoestrus t Metoestrus t 1 3 Metoestrus t Metoestrus t Metoestrus 610 2It 1 4 Metoestrus Dioestrus 603 S 1 S-14 Dioestrus 604 S Dioestrus S-14 Dioestrus Dioestrus Dioestrus Dioestrus Dioestrus 60S Dioestrus Dioestrus Dioestrus * Age estimated from size of corpora lutea (Restall 1964). t Marked for the second time by teasers on morning of slaughter. t Marked for the second time by teasers prior to slaughter. (c) Collection of Reproductive Tracts The ewes were slaughtered and placed on an abattoir chain. The entire reproductive tract was removed within 20 min of death, examined, and placed in a buffered formalin fixative (ph 7 4).

3 HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE 675 (d) Classification of Reproductive Tracts After consideration of the time of slaughter and the ovarian morphology (Restall 1964), each tract was classified as being in oestrus, metoestrus, dioestrus, or pro-oestrus. Metoestrus was arbitrarily considered to extend for 5 days and ovulation was considered to occur toward the end of oestrus. The classifications are given in Table 1. (e) I'reatment of Reproductive Tracts Some butchers removing the tracts from the ewes often damaged them such that they could not be used. Those tracts that were undamaged had tissue samples taken from the following sites: (1) the posterior vagina; (2) the anterior vagina adjacent to the cervical 01:1; (3) the posterior cervix 1 cm from the cervical os; (4) the middle portion of the cervix; (5) the anterior cervix 1 cm from the uterus; (6) the body of the uterus, midway between the cervix and the external bifurcation; (7) the right uterine horn, midway between the external birfurcation and the uterotubal junction; (8) the left uterine horn, as in 7; (9) the isthmus of the right fallopian tube, 3 cm from the uterotubal junction; (10) the right fallopian tube in the region of the ampulla-isthmic junction; (11) the ampulla of the right fallopian tube 2 cm below the tubal ostium; (12), (13), (14) the left fallopian tube as in (9), (10), and (11). These tissue samples were dehydrated, embedded in paraffin, and crosssections 4-6 fl thick were taken. Duplicate tissue sections were stained in two ways: (1) Using a rapid stain in dilute alcian blue, which is specific for mucopolysaccharides when used in this way. The tissue sections were given a 2-min premordant treatment in alcoholic picric acid, then hydrated and stained with Weigert's haematoxylin. After staining for 60 sec in 1 % aqueous alcian blue, the colour was fixed by treating the sections with alkaline alcohol for 2 hr. The sections were then counterstained with Van Giesen's stain. (2) Using periodic acid-schiff's reagent (P.A.S.) as a more general stain for secretory granules in cells. Each batch of P.A.S. was tested on sections of mouse gut prior to general use. (f) Measurement Technique Epithelial height was measured in three positions by the use of an eyepiece micrometer. The positions selected for measurement were, as near as could be evinced, cross-sections of the cells. In the vagina epithelial height was measured between stromal projections and in the uterus only the intercaruncular epithelium was measured. In the cervix and the fallopian tubes the number of stromal folds projecting into the lumen in the complete cross-section was noted. In the fallopian tube the stromal folds were subdivided into primary folds, i.e. those folds projecting from underlying stroma, and secondary folds, i.e. those folds branching off the primary folds.

4 676 B. J. RESTALL In the uterus the height of the glandular epithelium was measured in the necks of three glands. As well the number of gland coils was estimated by counting the number transecting an arbitrary line 200 J.L in length extending from the myometrium toward the centre of the lumen. In the vagina the number of cell layers was noted as well as the degree of cornification and desquamation and the presence of leucocytes. (g) Statistical Analysis Where possible all data were subjected to an analysis of variance. Because of missing and damaged portions of the reproductive tracts and some embedding failures, it was not possible to have ewes in each stage of the cycle with all 14 sample positions measured. Consequently measurements on the positions were treated as replications irrespective of whether they were from the same ewe or not. The subsequent correlation of errors was allowed for by using significant interaction mean squares to test main effects. Analyses were carried out by the method of unweighted means with an estimate of error being calculated from all measurements (Snedecor 1957). Analyses were carried out on data from within the portions of the tract designated vagina, cervix, uterus, and fallopian tube, each reading being classified as to position and stage of oestrus. III. RESULTS (a) Vagina The vagina was observed to have a stratified squamous epithelium with numerous epithelial projections extending into the underlying stroma (Plate 1, Fig. 1). These epithelial projections were more numerous in the posterior vagina. Desquamation of the epithelium occurred during oestrus and metoestrus (Plate 1, Fig. 1) and cornification was greatest at this time. Leucocytes were almost continually present in the stroma and there was a great variation in their number; they invaded the epithelium in great numbers when desquamation occurred. The height of the epithelium between buds varied from 13 to 128 J.L and analysis shows a position by stage of cycle interaction (Table 2). At oestrus the epithelium is higher in the anterior vagina. During pro-oestrus and dioestrus the height of the epithelium in the two regions is very similar. However, because of small numbers in this analysis the results must be accepted with caution. There was no evidence of secretory cells in the vagina, with the exception of the extreme anterior end at the entrance to the cervix. At this site cells of a cervical nature were observed to overlie the vaginal epithelium (Plate 1, Fig. 2). (b) Cervix The cervix was lined with a high columnar epithelium with numerous goblet cells (Plate 1, Fig. 3). The height of the epithelium was reduced during dioestrus (Table 3). The number of folds projecting into the lumen (Table 4) was also significantly less in the dioestrous stage of the cycle.

5 ~- - - HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE 677 TABLE 2 MEAN HEIGHT OF THE EPITHELIUM IN TWO POSITIONS IN THE VAGINA DURING THE OESTROUS CYCLE Oestrus Posterior Vagina Anterior Vagina No. of Height No. of Height Ewes (flo) Ewes (flo) Pro-oestrus Oestrus Metoestrus Dioestrus _.. _ Summary of the Analysis of Vm'iance Position in vagina (P) oestrus (S) PxS Error... P< '55* TABLE 3 HEIGHT OF THE EPITHELIUM IN THREE POSITIONS IN THE CERVIX DURING THE OESTROUS CYCLE Posterior Cervix Mid Cervix Anterior Cervix Oestrus No. of Height No. of Height No. of Height Ewes (,...) Ewes (,...) Ewes (flo) Pro-oestrus Oestrus Metoestrus Dioestrus ' I ---_.. _ ~ Summary of the Analysis of Variance _.. _--- - Position in cervix (P) oestrus (S) 3 14'05* PxS Error * P < 0'05, pro-oestrus = oestrus = metoestrus> dioestrus.

6 678 B. J. RESTALL During all stages of the cycle the goblet cells showed the presence of mucus, as evidenced by staining with P.A.S. and alcian blue (Plate 1, Fig. 4). During prooestrus mucus was evident in the lumen and could be seen streaming from the cells (Plate 1, Fig. 5). There were no differences in cell height or number of folds between the anterior, mid, and posterior portions of the cervix, although there were fewer goblet cells in the anterior cervix, the epithelium of which approached the type observed in the uterus. TABLE 4 MEAN NUMBER OF STROMAL FOLDS IN THREE POSITIONS IN THE CERVIX DURING THE OESTROUS CYCLE Posterior Cervix Mid Cervix Anterior Cervix Oestrus No. of No. of No. of No. of No. of No. of Ewes Folds Ewes Folds Ewes Folds Pro-oestrm' Oestrus Metoestrus Dioestrus _ I Summary of the Analysis of Variance Position in cervix (P) oestrus (S) 3 37'74** PxS Error ** P < 0 01; pro-oestrus = oestrus = metoestrus> dioestrus. (c) Uterus The lumen of the uterus was lined with a simple columnar epithelium with numerous glands in the intercotyledonary areas (Plate 1, Fig. 6). The glands were also lined with a columnar epithelium. The epithelium in the lumen and in the glands shows a cyclic variation in height (Tables 5 and 6). The lumenal epithelium is highest during pro-oestrus and lowest in dioestrus. The cell contents did not stain with P.A.S. or alcian blue although the lumenal fringes of the cell were faintly P.A.S.-positive. The epithelium of the glands showed a cyclic variation with the lowest height being observed in dioestrus. P.A.S.-positive material was observed in the glands during pro-oestrus, and they showed greatest proliferation, as evidenced by an increase in coiling (Table 7) at this time.

7 HISTOLOGY OF THE REPRODUOTIVE TRAOT OF THE EWE 679 TABLE 5 MEAN HEIGHT OF THE LUMENAL EPITHELIUM IN THREE POSITIONS IN THE UTERUS DURING THE OESTROUS OYOLE Oestrus Body of the Uterus Left Horn Right Horn No. of Height No. of Height No. of Height Ewes (1-') Ewes (1-') Ewes (1-') Pro-oestrus Oestrus Metoestrus Dioestrus Summary of the Analysis of Variance Position in uterus (P) oest,rub (13) ** PxS Error ** P < 0 01 ; pro-oestrus> oestrus = metoestrus> dioestrus. TABLE 6 MEAN HEIGHT OF THE GLANDULAR EPITHELIUM IN THREE POSITIONS IN THE UTERUS DURING THE OESTROUS OYOLE Oestrus Body of the Uterus Left Horn Right Horn No. of Height No. of Height No. of Height Ewes (1-') Ewes (1-') Ewes (1-') Pro-oestrus Oestrus ' Metoestrus Dioestrus Summary of the Analysis of Variance Position in uterus (P) oestrus (S) 3 35'48* PxS Error * P < 0 05; pro-oestrus = oestrus = metoestrus> dioestrus.

8 680 B. J. RESTALL (d) ~Pallopian Tube The fallopian tube is lined with pseudo stratified columnar epithelium which shows considerable cyclic variation and a variation in character along its length. Significant differences in the height of epithelium occur along the tube, with the isthmic epithelium being lower than that in the ampulla. Also there are significant differences in the height of the epithelium between stages of the cycle, with the tallest epithelium being recorded in oestrus and metoestrus (Table 8). No differences were observed between the left and right fallopian tube. TABLE 7 MEAN NUMBER OF GLAND COILS IN THREE POSITIONS IN THE UTERUS DURING THE OESTROUS CYCLE Oestrus Body of Left Horn Right Horn the Uterus No. of No. of No. of No. of No. of No. of Ewes Glands Ewes Glands Bwes Glands Pro-oestrus Oestrus a Metoestrus fj 14 3 U Dioestrus 4 15' < _.----_._ "-~ M.ean 17 8 Ifj Summary of the Analysis of Variance Position in uterus (P) oestrus (S) 3 27'79** PxS Error ** P < 0 01; pro-oestrus> oestrus> metoestrus dioestrus. The results of the analyses of mucosal folds are given in Tables 9, 10, and II. Folding increases significantly in the mid tube and ampulla regions; the isthmus contains only primary folds whilst there is a great increase in secondary folds in the positions further toward the ovarian end of the tube (Plate 2, Figs. 1 and 2). P.A.S.-positive material was seen throughout the cycle but was most intense during oestrus. In the ampulla and the mid-tube region, cytoplasmic projections were always present, but none was observed at any time in the isthmus (Plate 2, Figs. 3 and 4). Nuclei and the leucocyte-like cells described by Nellor (1965) were extruded in large numbers during dioestrus and pro-oestrus in the ampulla region (Plate 2, :Fig. 5). Only a sparse extrusion of nuclei and cells was noted at other times in the cycle.

9 HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE 681 IV. DISCUSSION The morphological changes observed here are in general agreement with those described in the literature. The disagreements in the literature are mainly concerned with the time the changes occur and this arises from considerations of the lengths of each stage of the cycle and the failure of some authors to consider individual variation. For instance Grant (1934) found some discrepancies between his observations TABLE 8 MEAN HEIGHT OF THE EPITHELIUM IN THREE POSITIONS IN THE FALLOPIAN TUBE DURING THE OESTROUS CYCLE Oestrus Tube Isthmus Mid Tube Ampulla No. of Height No. of Height No. of Height Ewes (1'-) Ewes (1'-) Ewes (1'-) Pro-oestrus Oestrus Metoestrus Dioestrus Left Right Left Right Left Right Left Right Summary of the Analysis of Variance oestrus (S) ** Tube (left v. right) (T) 2 66 Position in tube (P) ** Interactions-pooled Error ** P<O OI; ampulla = mid tube > isthmus; oestrus = metoestrus> pro-oestrus> dioestrus. and those of Cole and Miller (1935) and Casida and McKenzie (1932), particularly in the relation of vaginal cytological changes to the phases of the oest.rous cycle. Cole and Miller (1935) have considered metoestrus to be of about 10 days in length whilst most other authors have arbitrarily chosen a metoestrus of about 5 days. Considerations such as this reconcile some of the discrepancies noted. Disagreement of a more fundamental nature is expressed by Hadek (1955), who considers that secretion in the fallopian tube is not holocrine, a view expressed by Casida and McKenzie (1932) and McKenzie and Terrill (1937).

10 682 B. J. RESTALL While the fact emerges that variation exists in the time relation of the phases of the cycle and the cytological changes, the changes are nevertheless quite clear and are more pronounced and regular in some parts of the tract than in others. In the vagina this study and others in the literature indicate that no secretory cells are present except near the entrance to the cervix. Cole and Miller (1935) observed secretory cells in the vagina during pregnancy, but at no other time. TABLE 9 MEAN NUMBER OF PRIMARY FOLDS IN THREE POSITIONS IN THE FALLOPIAX TUBE DURING THE OESTROUS CYCLE Isthmus Mid Tube Ampulla Tube Oestrus No. of No. of No. of No. of No. of No. of Ewes Folds Ewes Folds Ewes Folds ---- Pro-oestrus Left Right Oestrus Left Right l() Metoestrus Left. 5 7 (j ri 16 6 [, IS'O Right Dioestru" Left 4 S O Right ~ Summary oj the Analysis oj Variance Position in tube (P) * oestrus (S) Tube (left v_ right) (T) Interactions Error * P < 0. 05; ampulla = mid tube> isthmus. The vaginal epithelium shows a constant change with an increase in the thickness of the epithelium occurring during oestrus and keratinization and desquamation following_ However, great variation exists and is quite regional (as noted by Grant 1934). but it is clear that the presence of oestrogen in the blood stream causes an increase in keratinization and desquamation_ The physiological significance of keratinization and desquamation is not clear, and possible analogies between the ewe and rodents are invalid because the time relations of coitus to the vaginal changes are different in the two species_

11 HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE 683 The cervix is well endowed with secretory cells which appear to continually contain mucus. This mucus is expelled during pro-oestrus, liquefies, and appears in the vagina at oestrus. Cole and Miller (1935) propose that pro-oestrus and oestrus can be separated on the basis of mucus flow. The present study would indicate that mucus continues to flow in early oestrus at least. These findings agree with Grant TABLE 10 MEAN NUMBER OF SECONDARY FOLDS IN THREE POSITIONS IN THE FALLOPIAN TUBE DURING THE OESTROUS CYCLE Oestrus Tube Isthmus Mid Tube Ampulla No. of No. of No. of No. of No. of No. of Ewes Folds Ewes Folds Ewes Folds Pro-oestrus Oestrus Metoestrus Dioestrus Left Right Left Right Left Right Left Right Summary of the Analysis of Variance Position in tube (P) ** oestrus (S) * Tube (left v. right) (T) 21 2 Interactions-pooled Error * P < 0 05; pro-oestrus = oestrus = metoestrus> dioestrus. ** p < 0. 01; ampulla> mid tube> isthmus. (1934) and a separation on the basis proposed by Cole and Miller (1935) would be untenable. The functions of cervical mucus may be: (1) to lubricate the vagina and so facilitate coitus; (2) to facilitate the passage of spermatozoa through the cervix. The uterus shows cyclical changes in the glandular epithelium and in the lumenal epithelium, greatest height being observed during pro-oestrus and oestrus. This is in agreement with Hadek (1958) and Cole and Miller (1935), but disagrees with Casida and McKenzie (1932) who found an increase in coiling during metoestrus

12 684 B. J. RESTALL and dioestrus. It is clear that the glands show secretory activity, but it is less clear that the epithelium has a secretory function. In this study, the epithelium showed a variation in height, but P.A.S.-positive material was not observed in the cells. Hadek (1958) noted a narrow layer of P.A.S.-positive material lining the lumen, but the possibility exists that this material was of glandular origin. The present study indicates that the fluid environment of the uterus is most likely to be of glandular origin. TABLE 11 MEAN NUMBER OF PRIMABY PLUS SECONDARY FOLDS IN THREE POSITIONS IN THE FALLOPIAN TUBE DURING THE OESTROUS CYCLE Isthmus Mid Tube Ampulla Tube Oestrus No. of No. of No. of No. of No. of No. of Ewes Folds Ewes Folds Ewes Folds Pro-oestrus Left Right Oestrus Left 4 U Right Metoestrus Left Right Dioestrus Left Right Summary oj the Analysi8 of Variance oestrus (S) Position in tube (P) ** Tube (left v. right) (T) Interactions-pooled Error ** P < 0. 01; ampulla> mid tube> isthmus. The fallopian tubes show striking morphological changes along their length. The greatest area of secretory epithelium occurs in the ampulla region with a vast number of mucosal folds and many secretory cells. The isthmic region appears to contain few secretory cells (also noted by Hadek 1955), and would appear to contribute little to the fluid environment. The cells of the ampulla continually secrete as evidenced by the continual presence of cytoplasmic projections. Extruding nuclei increase in number during dioestrus and pro-oestrus. P.A.S.-positive material is

13 HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE 685 always present, but is most intense during pro-oestrus and oestrus. These findings indicate that secretory activity would be maximal at these times. The observed morphological changes in the tract could reasonably be expected to facilitate and maximize the chances of conception. It is evident that secretory activity is at its peak at the time the gametes are in the tract, i.e. at oestrus. The cervical mucus would appear to fulfil two functions as it supplies a fluid environment in the vagina as well as in the cervix. The male gametes are only present in these portions of the tract during oestrus when a fluid environment is present. In the uterus secretion is evident again during pro-oestrus and oestrus but diminishes thereafter. The fluid environment thus provided could be expected to be primarily of importance in the physiology of sperm. When the embryo reaches the uterus there is evidence of a further increase in secretory activity (Lutwak-Mann 1959). Secretory activity is at a maximum in the fallopian tubes at oestrus and metoestrus and again would appear to be most important in the physiology of sperm and eggs at the time of fertilization. V. ACKNOWLEDGMENTS The assistance of the Riverstone Meat Co. Pty. Ltd. in supplying the experimental animals is gratefully acknowledged. Particular thanks are due to Mr. N. Watson, School of Wool Technology, University of New South Wales, for willing technical assistance. I am indebted to Mr. B. McGee, Universit,y of Sydney, for preparing the photomicrographs. This work was carried out while the author was the recipient of a General Motors Holden Post-Graduate Research Fellowship. VI. REFERENCES CASIDA, L. E., and McKENZIE, F. F. (1932}.-The oestrus cycle of the ewe; histology of the genital tract. Res. Bull. Univ. Mo. Agric. Exp. Stn. No COLE, H. H., and MILLER, R. F. (1935}.-Changes in the reproductive organs of the ewe with some data bearing on their control. Am. J. Anat. 57: 39. GRANT, R. (1934}.-Studies on the physiology of reproduction in the ewe. II. Changes in the vagina and cervix. Proc. R. Soc. Edin. 48: HADEK, R. (1955}.-The secretory process in the sheep's oviduct. Anat. Rec. 121: HADEK, R. (1958}.-Histochemical studies on the uterus of the sheep. Am. J. Vet. Re8. 19: 882. LUTWAK MANN, C. (1959}.-Biochemical approach to the study of ovum implantation in the rabbit. Mem. Soc. Endocr. No.6. p. 35. McKENZIE, F. F., and TERRILL, C. E. (1937}.-Estrus, ovulation, and related phenomena in the ewe. Res. Bull. Mo. Agric. Exp. Stn. No NELLOR, J. E. (l965}.-the leucocyte-like cells of the oviducts during the normal estrous cycle and their modification by progestin and estrogen treatment. Anat. Rec. 151: NOVAK, E., and EVERETT, H. S. (1928}.-Cyclical and other variations in the tubal epithelium. Am. J. Ob8tet. Gynec. 16: RESTALL, B. J. (1964}.-The growth and retrogression of the corpus luteum in the ewe. Aust. J. Exp. Agric. Anim. HU8b. 4: ROARK, D. B., and HERMAN, H. A. (1950}.-Physiological and histological phenomena of the bovine estral cycle with special reference to vaginal cervical secretions. Res. Bull. Mo. Agric. Exp. Stn. No SNEDECOR, G. W. (1957}.-"Statistical Methods Applied to Experiments in Agriculture and Biology." 5th Ed. (Iowa State College Press: Ames, Iowa.) SNYDER, F. F. (1923}.-Changes in the fallopian tube during the ovulation cycle and early pregnancy. Bull. John8 Hopkin8 Hosp. 34:

14 686 B. J. RESTALL EXPLANATION OF PLATES 1 AND 2 PLATE 1 Fig. I.-Epithelium of the vagina during oestrus. Desquamation of the epithelium is occurring and leucocytes have invaded the tissue. Fig. 2.-Epithelium of the vagina at the cervical os. Dark-stained cuboidal cells typical of the cervix can be seen overlying the vaginal epithelium. Fig. 3.-Epithelium of the cervix during oestrus showing numerous goblet cells. Fig. 4.-Epithelium of the cervix during pro-oestrus showing dark-stained mucus being expelled from the cells. Fig. 5.-Cervix during pro-oestrus showing a large amount of mucus on the cervical lumen. Fig. 6.-Uterus during pro-oestrus showing extensive glandular coiling in the intercotyledonary area. PLATE 2 Fig. I.-Isthmic region of the fallopian tube showing the small number of mucosal folds. Fig. 2.-Ampulla of the fallopian tube showing the characteristic extensive mucosal folding. Fig. 3.--Epithelium of the ampulla of the fallopian tube during metoestrus showing cytoplasmic projections on the cell surfaces. Fig. 4.-Epithelium of the isthmus of the fallopian tube during metoestrus showing absence of cytoplasmic projection. Cilia can be seen on the cell surfaces. Fig. 5.-Epithelium of the ampulla of the fallopian tube during metoestrus showing extensive extrusion of nuclei and leucocyte-like cells.

15 PLATE RESTALL HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE Aust. J. Biol. Sci., 1966, 19,

16 RESTALL PLATE 2 HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE Aust. J. Biol. Sci., 1966, 19,