Immunohistochemical study on the atretic and the growing follicles after experimental superovulation in rats I. Number of follicles by superovulation

Kwak, Soo-dong

Korean Journal of Veterinary Research 1997;37(1):71-78.

Soo-dong Kwak

Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University

과배란 유기된 rat 난소에 퇴축난포와 성장난포에 대한 면역조직화학적 연구 I. 동원된 난포수에 대하여

곽수동

경상대학교 수의과대학 동물의학연구소

Abstract

This study was designed to investigate the number of the growing and mature follicles following gonadotrophin treatments for superovulation in mature rats. Eighteen mature rats (Sprague-Duwely, initially 190~230gm) were randomly alloted into 3 groups. One group was control group, another FSH-treated group was injected intramuscularly with 0.5 units of follicular stimulating hormone (FSH) / rat, and third PMS and HCG-treated group was intramuscularly injected with 20~25IU of pregnant mare serum (PMS) / rat and then at the 48 hrs later, with 20~25IU of human chorionic gonadotrophin (HCG) / rat. The uteri and ovaries of rats were collected and then were observed grossly and serial sections of paraffin embedding ovaries were stained with H-E. Number of ovarian follicles by following 3 grades of large, middle and small follicles from secondary and tertiary follicles were investigated by LM photography of preparations. Small follicles were classified as secondary follicles of preantral follicles with more than 2 layers of granulosa cells surrounding the oocyte and middle follicles were classified as secondary follicles with early signs of antral cavity or with more than one small cavity on either side of the oocytes and large follicles were classified as tertiary follicles with a single medium sized antral cavity or large well-formed antral cavity. In gross findings, the uteri were slightly swelling in FSH-treated group and markedly swelling or filled with fluid in the uterine lumen in PMS and HCG-treated group. In histological findings, the shape and size of the follicles were diverse in middle and large follicles of FSH-treated group and PMS and HCG-treated group, and proportion of atretic follicles was increased in FSH-treated group and PMS and HCG-treated group than those in control group. The uteri of FSH-treated group and PMS and HCG-treated group were hypertropied or filled with fluid in the lumens and walls of uteri. The wall tissue layers were flattened and their blood and lymph vessels were dilated. The mean number of follicle per ovary in control group were appeared to be $17.1{pm}5.6$($14.0%{pm}4.6%$), $37.8{pm}9.1$($30.9{pm}7.4%$) and $67.6{pm}30.1$($55.2{pm}24.6%$) respectively at large, middle and small follicles and total number of these 3 grade follicles were appeared to be $122.5{pm}40.0$. The mean number of follicle per ovary in FSH-treated group were appeared to be $22.8{pm}7.0$($17.4%{pm}5.3%$), $43.4{pm}6.6$($33.2{pm}5.1%$) and $64.5{pm}13.0$($49.3{pm}9.9%$) respectively at large, middle and small follicles and total number of these 3 grade follicles were appeared to be $130.7{pm}16.6$. The mean number of follicle per ovary in PMS and HCG-treated group were appeared to be $29.7{pm}11.0$($16.3%{pm}6.0%$), $61.9{pm}17.2$($33.9{pm}9.4%$) and $91.1{pm}28.2$($49.9{pm}15.4%$) respectively at large, middle and small follicles and total number of these 3 grade follicles were appeared to be $182.6{pm}32.7$. The above findings reveal that large follicles were increased 29.8% in FSH-treated group and 73.7% in PMS and HCG-treated group than those in control group and in histologic findings, proportion of atretic follicles were more increased in ovaries with more number of more developing follicles.

Key Words: superovulation, uterus, ovary, follicle number, rat