Development of Female and Male Systems Flashcards
Define an embryo.
Has not yet acquired an anatomical form that is readily recognizable.
Define a fetus.
Presence of all major body organs. Recognizable as a member of a given species.
What are the 3 general steps in embryology?
Cell mass
Cell layers start flat
Organogenesis “outside” the embryo
What 3 cell lines are in the cell mass?
Endoderm
Mesoderm
Ectoderm
What cell lines give rise to the reproductive organs?
Ectoderm and mesoderm
What is schistosomus reflexus?
The organs never go into the body cavity, but the fetus develops to term. Spine is also bent the wrong direction. All this results in often severe dystocia.
T/F: The embryonic period is relatively similar in all species.
True. It is gestational length that differs.
During what trimester can you sex the fetus?
During the first trimester.
What is sex differentiation?
Process where a group of cells develops into a functional, recognizable group of cells.
What is sex determination?
Determines the sexual characteristics of an organism.
What is a karyotype?
The number and appearance of chromosomes.
What is a genotype?
Describes the alleles.
What is a phenotype?
Describes the observed characteristics. The expression of the genotype.
What is a chimera?
An organism with cells from two different zygotes.
What is a mosaic?
Two or more populations of cells with different genotypes in one individual that developed from a since fertilized egg.
What are the 3 stages of sexual differentiation?
Chromosomal sex/karyotype (XX or XY)
Gonadal sex
Phenotypic sex
What does the chromosomal sex tell you?
Just that the animal is chromosomally male or female
After what percent of gestation is the sex usually obvious?
After 15%
What does the reproductive tract develop close to and at the same time as?
The renal system.
What is the pronephros?
Primitive kidney, nonfunctional.
What is the mesonephros?
Intermediate kidney
What is the metanephros?
Final, functional kidney.
In the female and male, what happens to the mesonephric ducts (Wolffiean ducts)?
They regress in the female, and become the epididymus and ductus deferens in the male.
In the female and male, what happens to the paramesonephric ducts (Mullerian ducts)?
In the female, they become the uterus, oviducts and cranial vagina. In the male, they regress.
What happens to the primitive sex cords?
They regress in the female, and become the seminiferous tubules in the male.
What are the female primitive germ cells called?
Oocytes
What are the male primitive germ cells called?
Spermatogonia
What is the testis determining factor?
A sex determining region on the Y chromosome that stimulates the development of the male reproductive tract when present, or the development of the female reproductive tract if absent.
What is anti-mullerian hormone?
Stimulates differentiation of Leydig cells and degeneration of paramesonephric ducts.
What does dihydrotestosterone promote?
The development of a penis, scrotum and accessory sex glands.
Where in the body are the testis formed?
Near the ribs!
What structure do the oviducts, uterus and cranial vagina develop from and what cell type are they?
From the paramesonephric ducts
Mesoderm
T/F: The female gonads and ducts do not originate retroperitonaly.
False. They DO originate in the retroperitoneal space.
What occurs during fetal maturation?
The organs that were produced during the embryonic stage mature.
Male: Testicles descend into scrotum
Female: Broad ligament develops and ovaries migrate caudally.
During what trimester does testicular descent occur?
In the 2nd trimester for bulls and rams
In the 3rd trimester for boars and humans
In and beyond the 3rd trimester in colts
What structure helps pull the testis into the scrotum?
The gubernaculum
What are the 3 phases in testicular descent?
Growth and elongation of body away from testes
Rapid growth of extraabdominal gubernaculum
Shrinkage of the gubernaculum within the scrotum
What are 2 common testicular descent failures?
Cryptorchidism
Inguinal hernia
