Histological Changes of Ovary Through Last Days of Gestation in Rabbit
Total Page：16
File Type：pdf, Size：1020Kb
DOI : 10.35124/bca.2020.20.1.1349 Biochem. Cell. Arch. Vol. 20, No. 1, pp. 1349-1353, 2020 www.connectjournals.com/bca ISSN 0972-5075 HISTOLOGICAL CHANGES OF OVARY THROUGH LAST DAYS OF GESTATION IN RABBIT Riadh Lafta Meteeb1 and Aiman Mohammed Baqir Al-Dhalimy2 1Unit of Anatomy, College of Medicine, University of Kufa, Najaf, Iraq. 2College of Pharmacy, AL-Kafeel University, Najaf, Iraq. *e-mail : [email protected] (Received 11 August 2019, Revised 27 December 2019, Accepted 21 January 2020) ABSTRACT : This work was to show the shape of ovaries of rabbit at last period of pregnancy and to show relation between pregnancy and progress of follicles. In this study, we use twenty pregnant rabbit, five rabbit at age 22 days, 24 days, 26 days and 30 days of pregnancy. Then the ovaries get out of the body, fixed in 10% formalin and processed for microscopic study, which show that the cortex of ovaries was filled with a lot of follicles in different types and sizes. Also this study show that the numbers of primary and primordial follicle decrease with gestation. While the number of secondary follicles decrease through all stage of pregnancy. The morphometrical result shows increase in the number of tertiary follicles in the last day of pregnancy. Key words : Ovary, gestation, rabbit. INTRODUCTION follicles, which provide a basic knowledge to assist the Animals are divided as normal physiological ovulators reproductive study. (e.g. cattle, pigs, sheepand human) which undergo MATERIALS AND METHODS increase in estradiol that stimulates Gonadotropin We used twenty pregnancy rabbit, in different ages, releasing hormone (GnRH), which is release from the divide these rabbits into four groups, five for 22, 24, 26 hypothalamus, Luteinizing hormone (LH), is releasing and 30 days after gestation. These rabbits put in special from the anterior pituitary gland and in the end, the cages feeding the animal well, and expose to light for 16 ovulation of ovary are regardless of mating activity hours daily, then these rabbits killed and took ovary, weight (Brooks and McNeilly, 1994). Pituitary gland secret them, then processed by using paraffin wax, sections are luteinizing hormone, which is important to start ovulation stained by haematoxylin and eosin (H&E) and periodic (Bakker and Baum, 2008). acid Schiff stain (PAS) procedure. Using the microscoping The female rabbits are regarded as stimulated counting of follicles in different stage to determine its toovulators because after mating the ovulation occurred development (Gordon, 1982). (Spies et al, 1997 and Harkness et al, 2010) and rabbit Morphometric analysis have no regular cycle like other domestic species like For counting of ovarian follicles and based to cattle (Harkness et al, 2010). The period of receptivity classification of follicular in rodents by Pedersen’s, rodents in rabbit usually for 5-6 days (Myers and Poole, 1962) or follicles were divided into 3 major classification; small, 7-10 days (Harkness et al, 2010) in the loss of mating. (Primordial and Primary), medium (Preantral) and large The rabbit has two ovaries right and left, these lies (Antral or Graafian) follicles, respectively. in pelvic cavity laterally on left and right pelvic walls, RESULTS AND DISCUSSION each ovary covered with a basement membrane called tunica albuginea, beneath it, the ovarian tissue divided The ovaries were covered with epithelium, usually into outer cortex and inner medulla, the cortex consists consisted of simple cuboidal tissue (Fig. 1). The external of follicles and stroma, so there are more follicles at each layer contains large number of follicles. Corpora lutea stage higher ovulation rate (Danko, 1997). Zoubida et al were also seen (Fig. 2). In the central zone of ovarian (2009) shows that the histological changes that happened stroma, the medulla appeared vascularized. Spindle in uteri and ovaries of rabbits after birth in order to shaped stromal cells were mostly fibroblasts and also determine the effect of pregnancy on development of included bundles of smooth muscle cells (Fig. 3). This 1350 Riadh Lafta Meteeb and Aiman Mohammed Baqir Al-Dhalimy Fig. 1 : A Section of ovarian cortex of rabbit, stained with Methylene Fig. 2 : A Section of cortical stroma of rabbit show large number of blue. X400 follicles in different stages of development. X240. Fig. 3 : This Section shows medulla of ovary appeared spindle shape Fig. 4 : This figure show primordial follicles. X500. stromal cells. X90 finding is agreed with observation of Radwan, who cells (Fig. 6). The diameter of primary follicles can be described the histological structures in mouse ovary different according to the average diameter of the oocyte. (Radwan, 2010). These results explained that the oocyte increased in the In each stage of this study, the histological results largest primary follicles, began the maturation and the show numerous primordial follicles are observed at the growth process. Generally, this result of primary follicular edge area of the cortex (Fig. 4). Each one contained a formation is the same in other lab animals like rat (Cui primary oocyte, surrounded by two or three flattened and Yu, 1999), it was mentioned that the primary oocyte follicular cells (Fig. 5). These primordial follicles tend to grows large, resulting in multiple Golgi complex and be evenly distributed throughout the outer cortex. Some further proliferation of mitochondria and during this stage follicles possessed both flattened and cuboidal follicular of development the oocyte will increase its size by two cells. The analogous to this result has been described in or more times. As shown in (Table 1), the numbers of rabbit and in the ovary of non-pregnant does in herbivores, primordial and primary follicles become decrease with primordial follicles were regularly distributed through the progress of gestation. (Bahr et al, 1980) similarly noted outer cortex, by comparison, in carnivores the follicles that a progressive decline in the amount of follicles in the are more clustered (Boubekril et al, 2007). rabbit ovary that would respond to an LH-FSH sequence as the pregnancy continued, possibly for a loss of Primary follicles were also detected. Now, the gonadotropin- receptor activity. Nevertheless, it is oocytes weresurrounded with a thin zonapellucida, and a probable that the smaller sized follicles, which accumulate granulosahas taken shape as a single layer of cuboidal as pregnancy continues, secrete sufficient estrogen to Histological changes of ovary through last days of gestation in rabbit 1351 Fig. 5 : This figure show primary follicles which surrounded by Fig. 6 : This figure show oocyte surrounded with single layer of follicular cells. X240 cuboidal cells. X240 Fig. 7 : This figure show follicle surrounded with 2-3 cells thickness. Fig. 8 : This figure show follicle surrounded with many layers of X500 cells. X100 control luteal steroidogenic function (Setty and Mills, the biggest secondary follicles grew and increase its size 1987). by cells proliferation and accumulation of fluid in its center Through the histological examination by haematoxylin to form the antral follicle or tertiary follicle with single and eosin staining section of ovary, it was found that (Fig. 9). The part of cells surrounding the oocyte forming secondary follicles was present in all stages, these follicles cumulusoophorus, while peripheral cells near the characterized by presence of centrally located oocyte basement membrane formed the mural granulosa cells (which contain central nucleus). The size of the oocyte (Fig. 10). This result histologically is similar to progress was fixed in all follicles, but in small follicles the granulosa of preantral follicles to tertiary follicles through follicular was 2-3 cells thickness, zonapel lucida stained well with development in most rodents (Griffin et al, 2006). These periodic acid Schiff (Fig. 7). As these follicles grew, follicles don’t have periodic acid Schiff (PAS) positive granulosa cell division continue and the layers of cell bodies (Call-Exner bodies). increase in number forming stratified epithelium, 2 to 10- In Oryctalogus cuniculus, the large normal antral 12 layer cells thick (Fig. 8). This study show that follicles developed from the maturing follicles to form decreasesthe rate of formation of secondary follicles pre-ovulatory follicles. These pre-ovulatory follicles were through all stages of this study (20, 24, 26 and 30 days) characterized by these oocyte present in the center of of pregnancy compared with the primary follicles (Table the follicle and the germinal vesicle became eccentric in 1). This study agrees with Cui et al (2004), who described position. The granulosa cells surrounding the oocyte this in beef cow and buffaloes. So, this will indicate that formed a ring, the corona radiate. The oocyte was lie in the transformation of follicles in pregnancy process is the cumulus area (Fig. 11). low. The morphometric result show that the increase in Usually the follicle grew in the cortex of the ovary, the tertiary follicles in last day of gestation (3.25 ± 0.62) 1352 Riadh Lafta Meteeb and Aiman Mohammed Baqir Al-Dhalimy Fig. 9 : This figure show antral or tertiary follicle. X220. Fig. 10 : This figure show formation of cumulus oophorus. X200. Fig. 11 : This figure show formation of corona radiata. X220 Fig. 12 : This figure show atresia of primary and secondary follicles. X10 Table 1 : Follicular number counts in studied groups. Follicles Primordial follicles Primary follicles Secondary follicles Tertiary follicles Days of gestation 20 65.00 ± 1.77A 12.25 ± 0.62A 3.75 ± 0.47A 3.25 ± 0.62A 24 56.50 ± 1.32B 17.00 ± 0.40B 3.50 ± 0.28A 2.50 ± 0.28A 26 51.50 ± 1.70C 14.75 ± 0.62C 4.00 ± 0.40A 3.75 ± 0.47A 30 32.25 ± 1.31D 9.50 ± 0.64D 5.75 ± 0.47B 8.00 ± 0.40B Values represent mean ± S.E. Different capital letters mean significant differences at (p< 0.05) results between different periods.