amphibian gametogenesis

• two closely opposed membranes in the ovary

  Theca interna and theca externa
• elongated cells covering the surface of the growing oocyte

  Follicle cells
• help in nutrition of the oocytes and provide mechanical support

  Follicle cells
• very fine layer covering the oocyte and found beneath the follicle cells


  Vitelline membrane
• the nucleus of an oocyte

  Germinal vesicle
• the dots inside the Germinal vesicle are called

  amplified nucleoli
• seen as granules which are generally colored fuschia

  yolk
• what pushes the cytoplasm towards the periphery and immediately around the germinal vesicle

  yolk
• yolk pushes what around the germinal vescile?


  cytoplasm
• The tunica albuginea is the thick connective tissue that serves as the external covering of the testis
• spermatocysts enclose cells in the same stage of spermatogenesis
• the spermatocysts are attach to the basement membrane of the seminiferous tubule
• Residual spermatogonia are spermatogonia that have not undergone meiosis
• Residual spermatogonia are reserved supply for the next breeding season
• active spermatogonia are spermatogonia that are undergoing mitosis
• Active spermatogonia has large nuclei
• Leptotene: This is the start of the Meiotic Phase
• The distinguishing feature of Leptotene is the appearance of the thin threadlike chromatin
• Interstitial cells secrete testosterone upon stimulation of the luteinizing hormone from the anterior pituitary
• Sertoli cells function to nourish developing sperm.
• The end product of spermiogenesis is the spermatozoon
• in spermatozoa stage, the spermatid has reached its smallest size with compact chromosomes
• A tail develops at one end and an acrosome cap forms at the opposite end.
• Zygotene: facilitates crossing over of chromatin material
• In Pachytene stage, The chromatin has undergone a massive/extensive compacting
• In pachytene, nuclei will appear as raisin-like dark structures and are easily distinguished.
• Diplotene stage: members of the homologous pairs with segments of their partner chromatin separate
• Secondary spermatocytes are spermatids that have not yet undergone meiosis
• Secondary spermatocytes: These are the products of Meiosis I and haploid
• Type A: These cells look like Pachytene cells so they appear like raisins but smaller
• Type B: chromatin materials are seen attached to the nuclear membrane
• secondary spermatocytes undergo the second Meiotic division to form spermatids
• Spermatids are haploid
• Spermatids get rid of their cytoplasm and nucleoplasm as residual bodies in order to lighten their load and easily reach the oocyte
• Sertoli cells are cells not contained within spermatocytes. Small and irregularly shaped
• Leptotene: start of Meiotic Phase
• Diplotene: homologous pair separates again but remain connected at chiasmata
• Gametogenesis

  1. Production of functional ex cells (gametes) is vital for successful reproduction of a new individual

  2. Gametes are haploid cells containing one-half set of chromosomes formed in the testes of male organisms and ovaries of females

  3. Production of gametes involves a special type of cell division known as meiosis, which reduces the original chromosome number

  4. Gametes are physical carriers of genetic information transmitting parental characters from one generation to the next

  5. Gametogenesis involves two types: Oogenesis and Spermatogenesis
• Structures involved in Mammalian Oogenesis

  • Germinal epithelium
  • Tunica albuginea
  • Stroma
  • Follicles
• Mature or Graafian follicles

  • Antrum, Cumulus oophorus, Primary or secondary oocyte, Stratum granulosum, Corona radiata