SEM_15_Mammary Glands Development

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Questions and Answers

Where do the mammary glands of cows, sheep, goats, and horses typically located?

In the inguinal region (correct)

In the thoracic region

Spread throughout the ventral aspect of the trunk

In the abdominal region

How many inguinal glands with gland openings/teat do mares typically have?

2 inguinal glands with 1 gland opening/teat (correct)

4 inguinal glands with 1 gland opening/teat

3 inguinal glands with 2 gland openings/teat

1 inguinal gland with 2 gland openings/teat

In ruminants and horses, what are the mammary glands and teats collectively known as?

Ectoderm

Mammary papillae

Mammary lines

Udder (correct)

Where are the most productive mammary pairs located in sows?

Thoracic region Signup and view all the answers

Which hormone secreted by the testes in male embryos induces atrophy of the mammary buds?

Testosterone Signup and view all the answers

During prenatal development, the mammary bud sinks into the __________ precursor and expands to form a rudimentary duct system.

Mesenchymal Signup and view all the answers

What is the most common mammary anomaly in newborns?

Polythelia Signup and view all the answers

What is formed under the control of sex-related hormones during the onset of puberty?

Terminal end buds Signup and view all the answers

What provides the supporting connective tissue and vascular supply for the mammary glands?

Associated mesenchymal cells Signup and view all the answers

Which depression do multiple lactiferous ducts open into in humans during prenatal development?

Mammary pit Signup and view all the answers

What serves as a reservoir for milk just before entering the teat?

Gland sinus (ampulla) Signup and view all the answers

How many thoracic pairs do bitches have according to the given text?

2 Signup and view all the answers

What are formed by focal condensation and thickening of the ectoderm and subyacente mesenchyme along the mammary ridge?

Primary mammary buds Signup and view all the answers

What hormone plays a leading role in mammary development according to the given text?

Testosterone Signup and view all the answers

How many mammary openings are situated on the tip of each teat in bitches according to the given text?

12 Signup and view all the answers

What is the most common mammary anomaly in newborns?

Polythelia Signup and view all the answers

What hormone induces atrophy of the mammary buds in male embryos according to the given text?

Testosterone Signup and view all the answers

Where do multiple lactiferous ducts open into during prenatal development in humans?

Mammary pit Signup and view all the answers

What serves as a reservoir for milk just before entering the teat?

Gland sinus (ampulla) Signup and view all the answers

During pregnancy, under the influence of increased levels of estrogen and progesterone, what forms the mammary gland alveoli?

Terminal end buds Signup and view all the answers

What is the location of the mammary glands in mares?

Inguinal region Signup and view all the answers

How many mammary openings are situated on the tip of each teat in cats according to the given text?

5-6 Signup and view all the answers

Where are the most productive thoracic pairs located in sows?

Abdominal region Signup and view all the answers

What is the collective term for the mammary glands and teats in ruminants and horses?

Udder Signup and view all the answers

Where are the mammary glands of pigs and carnivores typically spread throughout?

Ventral aspect of the trunk Signup and view all the answers

What is the medical term for the failure of one or both testes to descend into the scrotum?

Cryptorchidism Signup and view all the answers

In males, under the influence of testosterone, what do the genital swellings become?

Penile urethra Signup and view all the answers

What do the urogenital folds beneath the genital tubercle become in females?

Labia minora Signup and view all the answers

What is the equivalent of labia minora in most domestic mammals?

Labia majora Signup and view all the answers

What forms the glans of the clitoris in females?

Penile urethra Signup and view all the answers

Which hormone influences the differentiation of male external genitalia?

Testosterone Signup and view all the answers

What does the urogenital orifice become in females?

Opening of the vulva Signup and view all the answers

What gives rise to the specific components of the phallus in males?

Mesenchyme inside the genital tubercle Signup and view all the answers

What forms the scrotum in males?

Genital swellings Signup and view all the answers

What does the genital tubercle become under the absence of testosterone (female scenario)?

Clitoris Signup and view all the answers

During which period of development are the primordial genital structures identical in the two sexes?

Gonadal stage Signup and view all the answers

What indicates male and female genetic sex in mammals?

XY indicates male and XX denotes female Signup and view all the answers

What is the precursor of the reproductive and urinary organs according to the text?

Intermediate mesoderm Signup and view all the answers

What process is preceded by the formation of temporary undifferentiated structures in the embryo?

Sex differentiation Signup and view all the answers

What is the medical term for the failure of one or both testes to descend into the scrotum?

Cryptorchidism Signup and view all the answers

What forms the glans of the clitoris in females?

Genital tubercle Signup and view all the answers

Where are the mammary glands of pigs and carnivores typically spread throughout?

Abdomen Signup and view all the answers

Which hormone plays a leading role in mammary development according to the given text?

Estrogen Signup and view all the answers

What hormone induces atrophy of the mammary buds in male embryos according to the given text?

Testosterone Signup and view all the answers

During prenatal development, what does the urogenital orifice become in females?

Vulvar cleft Signup and view all the answers

What is formed under the control of sex-related hormones during the onset of puberty?

Breast tissue Signup and view all the answers

What gives rise to the specific components of the phallus in males?

Bony tissue Signup and view all the answers

What is the role of Müllerian inhibiting hormone (MIS) in female embryos?

Suppresses the development of paramesonephric ducts Signup and view all the answers

What is the effect of testicular hormones on male embryos?

Suppress the development of paramesonephric ducts Signup and view all the answers

What structures do the testes stimulate to develop into the epididymides, vas deferens, and seminal vesicles?

Wolffian ducts Signup and view all the answers

What is responsible for the development of secondary sexual glands such as prostate and bulbourethral glands in males?

Mesonephric ducts Signup and view all the answers

What is the role of gubernaculum testis in the descent of testes?

Keeping a canal open for the descent of testes Signup and view all the answers

What can result from cryptorchidism if both testicles are undescended?

Sterility Signup and view all the answers

What is a potential consequence of undescended testicles?

Increased risk of torsion and cancer Signup and view all the answers

What can be used to identify undescended testicles?

Ultrasonography Signup and view all the answers

What is the purpose of neutering?

Prevent problems such as torsion and cancer Signup and view all the answers

When must testicular descent be completed in some species like humans?

Before birth Signup and view all the answers

What is referred to as a failure of one or both testicles to descend into the scrotum?

Cryptorchidism Signup and view all the answers

What can cryptorchidism result in if left untreated in both testicles?

Increased risk of cancer and torsion Signup and view all the answers

What triggers the development of testes in genetically male embryos (XY)?

Activation of the SRY gene on the Y chromosome Signup and view all the answers

In genetically female embryos (XX), what causes the development of ovaries?

Absence of the Y chromosome and SRY gene Signup and view all the answers

What is responsible for the complete differentiation of male genital ducts and sex-specific external genitalia?

Leydig cells Signup and view all the answers

What causes a decrease in testosterone production until the onset of puberty in males?

Differentiation of Sertoli cells Signup and view all the answers

What induces a second activation of Leydig cells and an increase in testosterone production required for secondary sex maturation in males?

Activation of the SRY gene Signup and view all the answers

Which cell population is present in gonads and originates at the gastrula stage?

Primordial germ cells (PGCs) Signup and view all the answers

What do primordial germ cells differentiate into in male embryos?

Spermatogonia Signup and view all the answers

What inhibits the development of female ducts and promotes the development of male genital ducts in male embryos?

Anti-Müllerian hormone (AMH) Signup and view all the answers

What are the two different cell populations present in gonads?

Primordial germ cells (PGCs) and Leydig cells Signup and view all the answers

What is responsible for suppressing the development of female ducts in male embryos?

Anti-Müllerian hormone (AMH) Signup and view all the answers

What is activated in genetically male embryos (XY) to induce the development of testes?

The SRY gene on the Y chromosome Signup and view all the answers

What causes a decrease in testosterone production before puberty?

Differentiation of Sertoli cells Signup and view all the answers

What is the process that forms the ovarian medulla?

Vascular stroma replaces the sex cords Signup and view all the answers

At what stage do the oogonia stop during the prenatal period?

Prophase stage of the first meiotic division Signup and view all the answers

What determines the reproductive life of females at birth?

Reserve of primordial follicles in the ovary Signup and view all the answers

From which ducts do the female genital organs develop without hormonal requirements?

Paramesonephric ducts Signup and view all the answers

What characterizes the development of the female genital tract and external genitalia in the absence of testicular influence?

Predetermined process Signup and view all the answers

What happens to remnants of mesonephric ducts in females according to the text?

Occasionally found in the wall of the vaginal vestibule Signup and view all the answers

At what stage do oogonia undergo mitotic activity?

During the prenatal period Signup and view all the answers

What forms a single-layered cuboid epithelium around each oogonium?

Supporting cells differentiate into follicular cells (granular cells) Signup and view all the answers

What gives rise to the specific components of the phallus in males?

Genital tubercle becomes glans penis under influence of testosterone Signup and view all the answers

What hormone plays a leading role in mammary development according to the given text?

Estrogen Signup and view all the answers

What becomes fused to form female genital ducts?

Paramesonephric ducts Signup and view all the answers

Study Notes

In the absence of a Y chromosome, the primordial gonadal cords in female embryos stop growing and become disorganized, leading to the formation of the ovary.
In the central region of the ovary, the sex cords disappear completely and are replaced by a vascular stroma, forming the ovarian medulla.
In the cortical region, the gonadal cords that remain close to the surface are dismantled, and their constituents (primordial germinal cells and supporting cells) are reorganized to form primordial follicles.
Primordial germinal cells differentiate into oogonia, which undergo mitotic activity during the prenatal period.
The female supporting cells differentiate into follicular cells (granular cells), forming a single-layered cuboid epithelium around each oogonium.
The entire population of oogonia enters the first meiotic division but stops at the prophase stage during the second third of gestation.
At birth, the mammalian ovary has a reserve of primordial follicles, which determines the reproductive life of females.
In the absence of testicular hormones, the female reproductive organs develop, and follicles form around the oogonia.
The female genital ducts, including the uterine tubes, uterine horns, and the uterine body, cervix, and cranial third of the vagina, develop from the paramesonephric ducts without any hormonal requirements.
The length of the paramesonephric ducts that become fused is species-dependent, with varying degrees of fusion among different mammals.
Occasionally, remnants of the embryonic mesonephric ducts can be found in the wall of the vaginal vestibule in females.
The embryo is potentially bisexual at the undifferentiated stage, with the presence of both mesonephric and paramesonephric ducts.
The development of the female genital tract and external genitalia is predetermined in the absence of testicular influence, but recent evidence suggests that it is not a completely passive process.

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Description

Learn about the development of mammary glands in both sexes and their origin from the mammary ridges. Understand how mammary papillae are formed as projections from the mammary ridges.