Histology of the ovary of the lesser short-nosed fruit bat (Cynopterus brachyotis)

TAN, NICOLE HAN XIN (2020) Histology of the ovary of the lesser short-nosed fruit bat (Cynopterus brachyotis). [Project Paper] (Submitted)

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Abstract

In mammals with the presence of a functional corpus luteum in one ovary all follicles in that ovary and in the second ovary will remain quiescent. The situation is different in the pregnant lesser short-nosed fruit bat (Cynopterus brachyotis). In this flying mammal when there is a functional corpus luteum in the ovary of the gravid uterine horn there are follicles at different stages of development in the ovary of the non-gravid uterine horn (Gopalakrishna, 1955). Based on the above the aim of the present study was to examine the histological structure of the ovary in this mammalian specie and delve into the significance of concurrent occurrence of functional corpus luteum and developing follicles in the ovaries of the pregnant fruit bat. Six female bats, three being pregnant were caught by trapping in the fruit plantation close to the 17th College, Universiti Putra Malaysia. Following laparoscopy the ovaries collected were processed for light microscopy. Histological sections of ovaries of non-gravid uterine horn revealed hundreds or probably thousands of primary follicles occupying almost a quarter of the ovarian parenchyma. The majority of these follicles were however degenerated as evidenced by pyknosis of follicular cell nuclei surrounding the oocytes. There were also secondary and tertiary follicles in the ovarian parenchyma but most of these follicles were atretic. In the ovary of the gravid uterine horn the entire ovarian parenchyma appeared to be occupied by luteal tissues except for some of atretic follicles at the periphery of the ovary. Three inferences could be drawn from the present study. Firstly, the histological structure and development of follicles in the ovary of this flying mammal were similar to those in other ground dwelling mammals. However a significant observation from this study and not reported in any other mammal until to date was the corpus luteum which occupied almost the entire ovarian parenchyma. Secondly, the numerous atretic follicles in the ovary of non-gravid uterus could be due to their inability to ovulate. Circulating progesterone secreted by the corpus luteum in the ovary of the gravid uterine horn prevented their ovulation and subsequently these follicles degenerate. With the degeneration of the follicles the concurrent occurrence of functional corpus luteum and developing follicles did not appear to have any significance in the pregnant fruit bat. Lastly, under normal circumstances, following parturition corpus luteum will involute and assume the structure of corpus albicans. The large corpus luteum which occupy almost the entire ovary of the gravid uterine horn will, following the birth of pups develop into a corpus albicans and the ovary will no longer be functional. As for the second ovary it will ovulate and form a corpus luteum; with ensuing pregnancy and following parturition the corpus luteum will also develop into a corpus albicans and the ovary will also become nonfunctional. Based on the histological structure of the corpus luteum and its development into a corpus albicans following parturition is there a possibility that the lesser short-nose fruit bat produces only two pups in its entire life time.

Item Type:	Project Paper
Faculty:	Faculty of Veterinary Medicine
Depositing User:	Ms. Nordeena Abdul Aziz
Date Deposited:	18 Oct 2023 03:19
Last Modified:	18 Oct 2023 03:19
URI:	http://psaspb.upm.edu.my/id/eprint/1447

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