Chapter 5: Sex Determination & Fetal Sexual Differentiation

Humans have _____ chromosomes, or _____ pairs?

Pairs 1-22 are called _____.

The 23rd pair is the _____ _____.

The _____ determines the genetic sex of the child.

The _____ _____ is contained in the Y Chromosome, and is the strongest determinant of sexual differentiation.

The first 7 weeks are the _____ _____ period, in which the SRY gene has not made the determination between ovaries and testes.

The presence of 2 X Chromosomes (XX) or 1X and 1Y Determined at fertilization.

All eggs contain __________.

All sperm contain _____.

The presence of either ovaries or testes; determined by chromosomal sex.

XX individuals form _____.

XY individuals form _____.

The conversion of the indifferent gonad into a testis or ovary.

Begins development in late 3 wee old embryo and develops from two tissues.

2 masses of somatic cells (supporting & steroidogenic) that form medial to the embryonic kidneys (mesonephros).

Contained in the yolk sac of the embryo. Will migrate around the 6th week into the genital ridge. Develop into germ cells (oogonia or spermatogonia).

Begins during the 7th week in XY embryo and is initiated by SRY gene on the Y Chromosome.

Steroidogenic cells form the ______ cells.

Leydig cells secrete ______.

Supporting cells form the ______ cells.

Sertoli cells secrete ______.

Why are they called supporting cells?

______ is very important for determining male internal genitalia.

______ form the spermatogonia 2n.

______ are arrested until puberty.

Begins during the 10th-12th week in XX embryo.

Formation of the ovary is initiated by ______.

In the formation of the ovary, the ______ gene is required to act on X.

Suppresses DMRT1, DMRT2 & SOX9 genes during formation of the ovary.

During formation of the ovary, steroidogenic cells will form ______ cells.

Theca cells synthesize ______.

In formation of the ovary, supporting cells form ______, or ______ cells.

Follicle (Granulosa) cells convert ______ to ______.

PGC's form ______.

Development of the internal & external genitalia.

______ ______ develop from paramesonephric ducts, mesonephric ducts & urogenital sinus.

Mullerian ducts are ______.

Wolffian ducts are _____.

Paramesonephric ducts are also known as ______ ducts.

Mesonephric ducts are also known as ______ ducts.

The XY (male) embryo develops ______ ______ during the 8th-11th weeks.

In the paramesonephric (Mullerian) ducts, ______ is needed to degenerate the female hormone in order for the embryo to become a male.

The mesonephric (Wolffian) duct is stimulated by ______ to form the ______, ______ & ______.

______ ______ is gained in the epididymis and remain there until ready to be utilized.

The ______ ______ is the transport for the sperm to the glands to form semen.

The ______ ______ are the first pair of glands in the male system and contribute the most fluid to add to the sperm in the testes.

The absence of ______ in the paramesonephric (Mullerian) ducts allow the ______, ______ ______, and the ______ to begin to form.

Develop from progenitor tissues that appear during the sexually indifferent stage.

In the XY embryo between 9-12 weeks, the penis is formed here.

In the XY embryo, the urethra, prostate & bulbourethral glands are formed here.

In the XY embryo, the scrotum is formed here.

______ and ______ act to form the external genitalia in the XY (male) embryo.

In the XX (female) embryo between 9-12 weeks, development of the external genitalia is ______.

In the XX (female) embryo, the clitoris is formed here.

In the XX (female) embryo, the lower 2/3 of the vagina is formed here.

In the XX (female) embryo, the Labia minora and Labia majora are formed here.

BOTH descend from their original positions high up in the abdomen.

Descent of the testes and ovaries depend on the _______.

Descent of the testes begins in the ______ month.

In the XY (male) embryo, _______ and ______ cause shortening of gubernaculum (ligamentous cord).

The ______ are completely descended by birth (95%).

______ is the failure of the testes to descend.

An error of sex determination, in this individual the autosomal testis determining genes (DMRT1, DMRT2 & SOX9) is defective and not suppressed by DAX1.

An error of sex determination, in this individual the SRY gene is absent (translocation error during meiosis).

An error of sex determination, in this individual the SRY gene is defective.

An error of sex determination, in this individual the SRY gene acts on the X chromosome (translocation error during meiosis)

In ______ ______, both ovarian & testicular tissue is present in the same individual (XX or XY).

In true hermaphroditism, the individual is most always ______.

Formed by the yolk sac, then migrate from yolk sac to genital ridges and develop into germ cells (oogonia or spermatogonia)

Arrival of ______ in genital ridges stimulates conversion of the indifferent gonad into a testis or ovary.

Steroidogenic cells that secrete testosterone.

Supporting cells that secrete APH

Steroidogenic cells that synthesize androgens

Supporting cells that convert androgens to estrogen

Chromosome pairs 1-22 are referred to as:

Formation of the ovaries requires which
of the following?

The migration of ____________from the ____________ into the genital ridge of the embryo around the 4-5th  week, begins
gonadal differentiation.

Around the 7th week in the XY embryo, the 2 cell types of the genital ridge will form the
testes.  What cells of the testes will the supporting cells become?

What hormone will the Leydig cells secrete?

Around the 10th week in the XX embryo, the 2 cell types of the genital ridge will form the
ovaries.  What cells of the testes will the steroidogenic cells become?

Internal genitalia will form the

The Paramesonephric duct is also referred to as the _________ duct.

What internal genitalia will form in the female from the paramesonephric duct?

What hormones are required for the internal genitalia of the female to form?

External genitalia will form the

What is necessary in order for the urogenital sinus to form the urethra in the XY embryo?

The urogenital folds form the ______________ in males and the ______________ in females.

What progenitor tissue later becomes the penis in males and the clitoris in the female?