Which one of the following statements about human sperm is correct?
Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilisation
The sperm lysis in the acrosome dissolve the egg envelope facilitating fertilization
Acrosome serves as a sensory structure leading the sperm towards the ovum
Acrosome serves as a sensory structure leading the sperm towards the ovum
B.
The sperm lysis in the acrosome dissolve the egg envelope facilitating fertilization
Penetration of human sperm is a chemical mechanism. In this, acrosome of sperm udergoes acrosomal reaction and release certain sperm lysins, which dissolves the egg envelope locally and makes the path for the penetration of sperm. Sperm lysins are acidic proteins. These sperm lysins contain a lytic enzyme hyaluronidase that dissolves the hyaluronic acid polymers in the intercellular spaces, which holds the granulosa cells of corona radiate together corona penetrating enzyme and acrosin.
The part of fallopian tube closest to the ovary is
isthmus
infundibulum
cervix
cervix
B.
infundibulum
The fallopian tubes, uterus and vagina constitute the female accessory ducts. Each Fallopian tube extends from the periphery of each ovary to the uterus, the part closer to the ovary is funnel -shaped infundibulum, which helps in the collection of the ovum after ovulation.
The second maturation division of the mammalian ovum occurs
shortly after ovulation before the ovum makes entry into the fallopian tube
until after the ovum has penetrated by a sperm
until the nucleus of the sperm has fused with that of the ovum
until the nucleus of the sperm has fused with that of the ovum
B.
until after the ovum has penetrated by a sperm
In mammalian ovum during maturation phase, meiosis occurs, nucleus shifts towards the animal pole and undergoes meiosis-I. After fertilisation (penetration of sperm), the second meiotic division is completed with unequal cytoplasmic cleavage. This forms a large cell the ootid with the essentially whole of the cytoplasm and a very small cell, the second polar body.
The signals for parturition originate from
placenta only
placenta as well as the fully developed foetus
oxytocin released from the maternal pituitary
oxytocin released from the maternal pituitary
B.
placenta as well as the fully developed foetus
The process of giving birth to a baby is called parturition. Parturition is induced by a complex neuroendocrine mechanism. The signal for parturition originates from the fully developed foetus and the placenta, which induce mild uterine contractions called foetal ejection reflex.
The first movements of the foetus and appearance of hair on its head are usually observed during which month of pregnancy?
Fourth month
Fifth month
Sixth month
Sixth month
B.
Fifth month
During development of the foetus in human by week 20, hair begins to grow including eyebrows and eyelashes, fingerprints develop. Fingernails and toe nails grow. Firm hand grip Between 16 and 20 weeks baby usually felt moving the for first time.