Ovary The ovary is composed of two parts: Outer cortex : houses the follicels. Inner medulla: is the middle region composed of connective tissue, blood vessels and lymphatics. Ovary is the female gonad or sex gland. Gonad: an organ that produces gametes; a testis or ovary. gametes (sex cells), ovum in females and spermatozoon in males. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 1
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Folliculogenesis Pre-antral Phase Antral Phase 26-Feb-18 Unilayer primary follicle Multilayer primary follicle Secondary follicle Early Antral Late Antral Preovulatory Dr. Mu`ath Alghadi, PhD. 7
Primordial follicle: Single layer of flattened follicular squamous cells (granulosa cells) surrounds the primary oocyte and segregated from it by the basal lamina. Primary follicle: The oocyte growth rapidly and increase in diameter, the nucleus enlarges and is then called a germinal vesicle, the follicular cells form a single layer of cuboidal cells. Secondary (preantral) follicle: Follicular cells proliferate by mitosis and form stratified follicular cells (granulosa layer), a thick coat of glycoproteins surrounds the oocytes (Zona pellucida). 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 8
Tertiary (Early antral ) follicle: The stroma immediately around the follicle differentiate into two layers; theca interna and theca externa, follicular fluid start to accumulates between the cells inside cavities. These cavities coalesce in one large cavity (antrum). Mature preovulatory follicle (16-25mm): Follicular cavity increases in size, and the oocyte adheres to the wall of the follicle by a small pedicle of cells (cumulus oophorus). The granulosa cells that are close contact with zona pellucida around the ovum become elongated and form the corona radiate, which accompanies the ovum when it leaves the ovary. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 9
Ultrastructure of Graafian follicle Theca Folliculi (fibrovascular layer) Theca externa Theca interna Membrana Granulosa Several layers of granulosal cells Antrum contain follicular fluid Cumulus oophorus A cluster of cumulus cells that surround the oocyte both in the ovarian follicle and after ovulation The innermost layer of the cumulus oophorus that directly adjacent to the zona pellucida called corona radiata Ovum (secondary oocyte) 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 10
Ultrastructure of the ovum Corona radiata Long processes Zona pellucida Plasma membrane Microvilli Nucleus (Germinal vesicle) CR Nucleolus (Germinal spot) Cytoplasm (Ooplasm) GV ooplasm ZP PM 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 11
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Folliculogenesis 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 13
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TESTIS H&E SEMINIFEROUS TUBULES 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 18
TESTIS H&E SEMINIFEROUS TUBULES SEMINIFEROUS TUBULES INTERSTITIAL TISSUE 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 19
TESTIS H&E SEMINIFEROUS TUBULES SEMINIFEROUS TUBULES INTERSTITIAL TISSUE 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 20
Convoluted portion of tubular compartment Two types of cells A. Somatic cells (Sertoli cells) B. Germ cells 1. Spermatogonium 2. Primary spermatocytes 3. Secondary spermatocytes 4. Spermatids 5. sperm 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 21
SEMINIFEROUS TUBULES 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 22
Sertoli cell Leydig cell Seminiferous tubules 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 23
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The mature spermatozoon averages about 0.03 mm. in length. It has an elongated, solid-staining head (nucleus) with an anterior acrosome, pointing outwardly toward the periphery of the seminiferous tubule. The short middle piece generally is not visible but the tail appears as a gray filamentous extension into the lumen, about four or more times the length of the sperm head. Frog spermatozoon Total length 0.03 to 0.04 mm. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 29
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Ovaries of the frog are paired, multi-lobed organs, Each lobe of the ovary is hollow and its cavity is continuous with the other 7 to 12 lobes. Ovaries are small structures consisting three layers: 1. Outer theca external 2. Middle germinal epithelium 3. Inner theca internal From middle germinal epithelium, single epithelium cell enlarges and forms the egg. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 31
Eggs are formed from the germinal epithelium. They become mature after passing through the following stages: 1. Multiplication phase: Genital epithelium divides into numerous cells called oogonia by mitotic division. 2. Growth phase: After absorbing nutrients, these cells become large which are called primary oocytes. 3. Maturation phase: In the first meiotic cell division each cell is divided into a large secondary oocyte and smaller known as first polar bodies. The first polar bodies disintegrate. The second meiotic division produces the ovum proper and the second polar body. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 32
The theca interna surrounds each egg except for the limited area bulging toward the body cavity, where it is covered by only the theca externa. This is the region which will be ruptured during ovulation to allow the egg to escape its follicle into the body cavity. The theca interna, plus the limited covering of the theca externa, and the follicle cells together comprise the ovarian follicle. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 33
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Classification Of Eggs Based Upon Amount of Yolk Egg Type Representative Organisms a) Alecithal - Almost without yolk. Placental mammals b) Meiolecithal - Small amount of yolk. Echinoderms, amphioxus, marsupials c) Mesolecithal - Moderate amount of yolk. Lung-fishes, frogs, and toads. d) Polylecithal - Very large amounts of yolk. Sharks, bony fishes, reptiles, birds, insects. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 39
Classification Of Eggs Based Upon Distribution of Yolk a) Isolecithal or Homolecithal - Yolk is evenly distributed. Occurs in the alecithal and meiolecithal eggs of echinoderms, amphioxus, marsupials, and other mammals. b) Telotecithal - Yolk is concentrated on one end of the egg, the vegetal hemi-sphere, with the cytoplasm plus the nucleus concentrated the at other end, the animal hemisphere. Occurs in the meiolecithal and polylecithal eggs of frogs, toads, birds, reptiles etc. c) Centrolecithal - Yolk is in the center of the egg, with cytoplasm around it. Example: Insect eggs 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 40
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2mm in diameter Two vitelline membranes bound the egg, which is encircled by albumen. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 42
Each egg has two colours, white is due to yolk that lies downward and black part is of less weight that lies on the surface of the water. These are also called vegetal and animal pole respectively. Unfertilized egg of Xenopus has a polarity along the animal vegetal axis 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 43
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Paired testes in males 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 45
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SG, Spermatogonia PS, Primary spermatocyte Ss, Secondary spermatocyte MS, Mature spermatocyte L, Lumen 26-Feb-18 Dr. Mu`ath Alghadi, PhD. original magnification 800 50
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Egg production Most avian species retain only the left ovary, oviduct, and shell gland at hatch (with exceptions) In early stages of embryonic development, each female bird has two ovaries; only the left one develops into a functional organ. A mature ovary looks like a cluster of grapes. and may contain up to 4,000 small ova which can develop into mature ova. Variation among bird species in the relative amount of yolk in eggs and the amount of energy available to the developing embryo 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 54
Reptiles and birds - ovaries solid but develop irregular, fluid-filled lacunae (cavities); eggs discharged into coelom Mammals - ovaries compact; no large chambers or lacunae 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 55
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The oviduct opens medially to ovary in a funnel-shaped ostium. Ovulation results in the release of an egg from a mature follicle on the surface of the ovary. The egg, is picked up by the ostium and ciliary currents carry it into the magnum region. Over about three hours the egg receives a coating of albumen. The egg then passes into the isthmus, where the shell membranes are deposited. This takes about one hour. The egg them moves to the uterus, or shell gland, where the calcareous shell is added and, in some birds, pigment is added in characteristic patterns. The egg then passes into the vagina and cloaca for laying. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 57
Ovary consist from basophilic cortex, while the medulla is more eosinophilic. The ovarian medulla consists of connective tissues, blood vessels, nerves and smooth muscle. The ovarian cortex contains a different follicular development stages from primordial follicles, small white follicle, small yellow follicles to large, yellow, yolk-filled pre-ovulatory follicles. Large follicles protrude from the surface of the ovary on short stalks while small follicles bulge from the surface. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 58
Five pre-ovulatory follicles are present (F1 F5). Small yellow follicles (SYF) and a regressing post-ovulatory follicle (RF). 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 59
A Ovary with large pre-ovulatory follicles (yellow), small yellow follicles (white), small white follicles (grey) B hilus region of ovary where nerves and vessels enter the ovarian medulla C Wolffian remnant tissues D infundibulum of the oviduct; E magnum of the oviduct; F isthmus of the oviduct; G shell gland; H cloaca. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 60
The more eosinophilic medulla of the mature laying hen ovary can usually be distinguished from the more basophilic cortex containing the follicles. This image also includes small white (SWF), primary (PF), 26-Feb-18 primordial (unlabeled), and regressing (RF) follicles. H & Dr. Mu`ath Alghadi, PhD. E. 40. 61
Cuboidal ovarian surface epithelium adjacent to a small white follicle (SWF) and a primordial follicle (Pr). H & E 26-Feb-18 400 Dr. Mu`ath Alghadi, PhD. 62
The simple cuboidal ovarian surface epithelium (OSE) overlying primordial follicles 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 63
The image includes a small white follicle (SWF) and a primordial follicle (Pr). A single layer of granulosa cells (GC) delineates each follicle. The small white follicle is also surrounded by theca interna and theca externa 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 64 layers. Luteal cell clusters (LC) are visible in the theca interna layer. H & E. 400.
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Germinal Period Cleavage is a series of rapid mitotic divisions wherein the enormous volume of zygote cytoplasm is divided into numerous smaller cells called blastomeres, by the end of cleavage, they form a sphere known as a 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 69 blastula (blastocyst)
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Morula 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 76
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Secondary Oocytes Fluid Filled Cavity Zona Pellucida Blastocyst consists of a large number of blastomeres arranged to form a hollow sphere. Group of cells localized inside one pole called inner cell mass, the surface cells of blastula are trophoblasts where the fluid filled cavity is called a blastocoele. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. Hatching Blastocyst 83
Formation of the blastocyst Sodium channels appear on the surface of the outer trophoblast cells; sodium and water are pumped into the forming blastocoele. 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 84
inner cell mass blastocoele Early blastocyst Later blastocyst 26-Feb-18 Dr. Mu`ath Alghadi, PhD. 85