Humans semen is liquid at ejaculation but it soon coagulates and then undergo secondary liquefaction under the influence of ..... Secretion released by ..... gland.

Options

A. Fibrinogen, seminal vesicle
B. Uterine milk, mucus
C. Fibrinolysin , prostate gland
D. Alkaline phosphatase , uterus

Answer

To solve the question regarding the coagulation and liquefaction of human semen, we will break down the process step by step.

### Step 1: Understanding Semen Composition
Human semen is a complex fluid that contains sperm cells and various secretions from male reproductive glands. At the time of ejaculation, semen is initially in a liquid state.

**Hint:** Consider the components of semen and their functions.

### Step 2: Coagulation of Semen
After ejaculation, semen undergoes coagulation. This process is essential for the retention of sperm within the female reproductive tract, increasing the chances of fertilization.

**Hint:** Think about what substances might cause coagulation in biological fluids.

### Step 3: Identifying the Coagulating Agent
The coagulation of semen is primarily influenced by a protein called fibrinogen. However, it is important to note that while fibrinogen contributes to coagulation, it is not the only factor involved in the subsequent liquefaction process.

**Hint:** Look for proteins or enzymes that play a role in both coagulation and liquefaction.

### Step 4: Secondary Liquefaction
After the initial coagulation, semen undergoes secondary liquefaction. This process allows sperm to become motile and is crucial for successful fertilization. The enzyme responsible for this liquefaction is called fibrinolysin.

**Hint:** Consider what enzymes are involved in breaking down proteins and facilitating liquefaction.

### Step 5: Source of the Enzyme
Fibrinolysin is secreted by the prostate gland. The prostate gland plays a significant role in the male reproductive system by producing fluids that nourish and transport sperm.

**Hint:** Identify which gland is responsible for producing the enzymes that affect semen consistency.

### Conclusion
The correct answer to the question is:
- **Fibrinolysin** is the secretion that influences secondary liquefaction.
- **Prostate Gland** is the gland that releases this enzyme.

### Final Answer
**Fibrinolysin** released by the **Prostate Gland**.