Histological Observations on the Reproductive Tract of the Ewe

Abstract

SummaryAn 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. INTRODUOTIONThe 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 1955Hadek , 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) AnimalsThirty-seven mature Merino ewes of similar origin were used. (b) TreatmentA 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 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. (c) Collection of Reproductive TractsThe 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). HISTOLOGY OF THE REPRODUCTIVE TRACT OF THE EWE (d) Classification of Reproductive TractsAfter 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 TractsSome butchers removing the tracts from the ewes often damaged them such that they ...

Vaginal Histological Changes after Using Intravaginal Sponges for Oestrous Synchronization in Anoestrous Ewes

“…There was no difference on the histological samples obtained from ewes that came into oestrus or not. Although the histological pattern of the animals that came into oestrus was similar to that observed during a normal oestrous cycle, those that did not come into oestrus and were sampled 72 h after IS withdrawal also had inflammatory characteristics (Restall ). In that sense, Restall () reported that the vaginal epithelium shows an increase in the thickness of the epithelium occurring during oestrus, followed by keratinization and desquamation.…”

“…Although the histological pattern of the animals that came into oestrus was similar to that observed during a normal oestrous cycle, those that did not come into oestrus and were sampled 72 h after IS withdrawal also had inflammatory characteristics (Restall ). In that sense, Restall () reported that the vaginal epithelium shows an increase in the thickness of the epithelium occurring during oestrus, followed by keratinization and desquamation. The similarity between these two groups (came into oestrus or not) confirms that the pattern observed even 72 h after IS withdrawal is a consequence of the conditions generated by the treatment, and not just by the hormonal changes that occurred later.…”

“…It should be considered that until that moment, ewes were under an artificial luteal phase provoked by the progestagen. By this moment, vaginal epithelium should have the lower height and presence of flat cells with low cornification (Hawkins and Darlow ; Restall ). In agreement with our results, the vaginitis provoked by the introduction of even a placebo IS in the vagina of the ewe could explain the decreased fertility (Manes et al.…”

Polyspermic Fertilization Following Tubal Surgery in Pigs, With Particular Reference to the Role of the Isthmus

“…But evidence from studies in vivo and in vitro suggests strongly that the secretions essential for the fertilization and early development of the egg are furnished by the ampulla rather than the isthmus, the former having been shown in a number of species to be the most active secretory region of the entire oviduct (e.g. for the ewe: Hadek, 1955;Restall, 1966;Restall & Wales, 1968). Furthermore, Whittingham (1968) has reported that mouse zygotes degenerated when cultured within the explanted isthmus, whereas the explanted ampullar region of the tube was able to support develop¬ ment, and he commented that the paucity or absence of secretory cells in the mouse isthmus could explain this situation.…”

The Fallopian Tube of the Sheep. V. Secretion From the Ampullla and Isthmus

“…The fallopian tube also shows morphological differences along its length, the secretory cells being mainly contained in the ampulla region (Hadek 1955;Restall 1966c). The epithelia of the isthmus and ampulla also appear to respond differently to oestrogen (Restall 1966b).…”