1
Question
Which of the following ideally doesn’t occur during a menstrual cycle?
Which of the following ideally doesn’t occur during a menstrual cycle?
Open in App
Solution
The correct option is C Loss of zona pellucida, and corona radiata
During a healthy menstrual cycle, regardless of the duration of the cycle, there won’t be any loss of zona pellucida and corona radiata layers from the secondary oocyte. During ovulation, when the oocyte is released from the Graafian follicle, it escapes along with its protective layers. These layers remain intact till the oocyte has been fertilised by the sperm. Fertilisation occurs in the ampulla of the oviduct, after which the zygote starts its journey towards the uterus. During this journey, the zygote loses corona radiata. Zona pellucida layer is typically lost in the uterus. It is so because the implantation is possible after the degeneration of the zona pellucida layer. So, the loss of corona radiata and zona pellucida are “post- fertilisation” events. They occur only if the ovum is fertilised.
The endometrium of the uterus can be divided into 2 layers- stratum basalis and stratum functionalis. During the menstrual cycle, the stratum functionalis, which lines the uterine cavity, consisting of cells like epithelial, stromal and vascular, expands and vascularises and is subsequently cast off during the process of menstruation. Note that the onset of menstrual cycle is triggered by the decrease in the levels of estrogen and progesterone which in turn leads to the synthesis of prostaglandins thereby constricting the spiral arterioles. When stratum functionalis is sloughed off , the stratum basalis remains relatively constant, complete with stem/progenitor cells which will be sourced upon to build the next endometrial later. So clearly, this event occurs during the menstrual cycle.
If the egg is not fertilised, the corpus luteum stops secreting progesterone and decays after approximately 10 days in humans. Referred to as an ovarian scar, the entire connective tissue of the corpus luteum is broken down through a process called luteolysis by macrophages, fibroblasts and type I collagen into a white mass called corpus albicans.
During a healthy menstrual cycle, regardless of the duration of the cycle, there won’t be any loss of zona pellucida and corona radiata layers from the secondary oocyte. During ovulation, when the oocyte is released from the Graafian follicle, it escapes along with its protective layers. These layers remain intact till the oocyte has been fertilised by the sperm. Fertilisation occurs in the ampulla of the oviduct, after which the zygote starts its journey towards the uterus. During this journey, the zygote loses corona radiata. Zona pellucida layer is typically lost in the uterus. It is so because the implantation is possible after the degeneration of the zona pellucida layer. So, the loss of corona radiata and zona pellucida are “post- fertilisation” events. They occur only if the ovum is fertilised.
The endometrium of the uterus can be divided into 2 layers- stratum basalis and stratum functionalis. During the menstrual cycle, the stratum functionalis, which lines the uterine cavity, consisting of cells like epithelial, stromal and vascular, expands and vascularises and is subsequently cast off during the process of menstruation. Note that the onset of menstrual cycle is triggered by the decrease in the levels of estrogen and progesterone which in turn leads to the synthesis of prostaglandins thereby constricting the spiral arterioles. When stratum functionalis is sloughed off , the stratum basalis remains relatively constant, complete with stem/progenitor cells which will be sourced upon to build the next endometrial later. So clearly, this event occurs during the menstrual cycle.
If the egg is not fertilised, the corpus luteum stops secreting progesterone and decays after approximately 10 days in humans. Referred to as an ovarian scar, the entire connective tissue of the corpus luteum is broken down through a process called luteolysis by macrophages, fibroblasts and type I collagen into a white mass called corpus albicans.
Suggest Corrections
0
Similar questions
View More
Join BYJU'S Learning Program
Explore more
Join BYJU'S Learning Program
