The cellular structure that was visible in the transmission electron micro graph but not visible in the cells when microscope was used is NUCLEOLUS.
The transmission electron micro graph is a microscopy method that involves using electrons beams to form image of specimens. Transmission electron micro graph can be used to view minute structures of the cell because of its higher optical capacity.
The nucleolus was not seen under the microscope because is a very small cell structure.
Answer: Hypothalamus
Explanation: The interface between the neural and endocrine systems is the hypothalamus, which through the pituitary gland controls the function of the peripheral endocrine glands. The hypothalamus, as a component of both the neural and endocrine systems, monitors the hormones secreted by the endocrine system, i.e. endocrine glands, to provide feedback that goes to the brain for processing. The pituitary gland, as one of the endocrine glands, is also controlled by the hypothalamus, meaning that the hypothalamus controls the secretion of hormones into the blood based on the needs determined by the processed brain data.
The cells that were involves in the process of spermatogenesis is
primary spermatocyte.
Both are extremely similar but have small changes that make all of the difference.
You've probably heard about how our bone structure is similar to many other animals', and likewise about our DNA.
When you observe these small changes, you will find organisms similar to each other where one little thing changes, and then another organism where there's <em>another</em> change, but that first change is also present. You can interpret evolution over different species just by looking at what's different in the bone structure as well as the genes and proteins.