T1. Comparative & Developmental Reproductive Anatomy Flashcards
Both male and female reproductive systems are derived from the same “sexually indifferent tissue”
What is it?
The urogenital ridge becomes the indifferent gonad
During embryonic development, sexual differentiation involves _____ only but not _____
Involves morphology only but not function
Define phenotype
the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
Sexual differential development of both sexes is underpinned by two co-existing features. Name and describe them
Homology in morphology and function: homology means that a lot of the structures come from the same thing, i.e. a bat wing, whale fin, and human hand are all homologues. There is a degree of similarity, a correspondence in position or structure.
Sexual dimorphism: Differences in two sexes of the same species beyond the difference in sexual organs. A good example is males being taller and more muscular on average, etc. Sexual dimorphism can be selected for, like the vibrant displays of birds of paradise
Which organ produces gametes in males, which in females?
What are gametes?
Testis in males, ovaries in females.
Gametes are a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Gonads are derived from three sources, what are they?
Mesothelium (mesodermal epithelium) lining the posterior abdominal wall
Underlying mesenchyme (embryonic connective tissue)
Primordial Germ Cells (earliest undifferentiated sex cells) - from coelom
Describe what the indifferent gonads are
Primordial organs (meaning it is before differentiation). Initial stages of gonadal development occur in **5th week**
Thickened area of mesothelioma develops on the medial side of the mesonephros (middle kidney)
There is proliferation of mesothelium and the underlying mesenchyme, producing a bulge called a gonadal (genital) ridge
Gonadal cords (fingerlike epithelial cords of cells) grow into underlying mesenchyme
Indifferent gonads now consist of external cortex and internal medulla
In XX embryos the cortex differentiates into the ovary, and the medulla regresses
In XY embryos, the medulla differentiates into a testis, and the cortex regresses
The indifferent gonads consist of a cortex and a medulla. State which part develops (and into what) and which part regresses in XX and XY embryos
In XX embryos the cortex differentiates into the ovary and the medulla regresses
In XY embryos the medulla differentiates into a testis and the cortex regresses
In what week does the initial stages of gonadal development of the indifferent gonads occur?
5th week
Gonadal cords, which are fingerlike epithelial cords of cells, become ______ in males
The parts of the gonadal cords that enter the medulla of the testis become?
Seminiferous cords (primordia of seminiferous tubules)
The parts of the gonadal cords that enter the medulla of testis become rete testis
Spermatagonia are derived from?
Sertoli cells are derived from?
Spermatagonia are derived from primordial germ cells
Sertoli cells are derived from mesenchyme
What is mesenchyme?
Mesenchyme is a type of connective tissue found mostly during embryonic development of bilateral animals (triploblasts). It is composed mainly of ground substance with few cells or fibers
Mese = middle, chyme = flesh/infusion
What is mesothelium?
the surface layer of the embryonic mesoderm, from which the mesothelium is derived.
Forms the visceral and serous pericardium, visceral and parietal pleura, visceral and parietal peritoneum, and the tunica vaginalis in men
