In Periplaneta americana, the blood vascular system is of ____A_______ type. Blood vessels are ______B__________. The visceral organs are located in ________C________ . ________C__________ is filled with a fluid which is composed of __________D______ and _________E________ .

Options

A. `{:(A,B,C,D,E),("Closed","Absent","Enterocoel","Plasma","Haemocytes"):}`
B. `{:(A,B,C,D,E),("open","Poorly developed","Haemooel","RBC","Haemolymph"):}`
C.
D. `{:(A,B,C,D,E),("open","Poorly developed","Haemooel","plasma","Haemocytes"):}`

Answer

To solve the question regarding the blood vascular system of Periplaneta americana (the cockroach), we will fill in the blanks step by step.

### Step-by-Step Solution:

1. **Identify the Type of Blood Vascular System:**
- The blood vascular system in Periplaneta americana is of an **open type**. In an open circulatory system, blood (hemolymph) is not confined entirely to blood vessels but flows freely through cavities called hemocoels, bathing the organs directly.

**Answer for A:** Open

2. **Describe the Blood Vessels:**
- In Periplaneta americana, the blood vessels are **poorly developed**. Although there are some blood vessels, they do not play a significant role in the circulation of blood as seen in closed circulatory systems.

**Answer for B:** Poorly developed

3. **Locate the Visceral Organs:**
- The visceral organs in Periplaneta americana are located in the **hemocoel**. The hemocoel is the body cavity that contains the hemolymph and allows it to circulate around the organs.

**Answer for C:** Hemocoel

4. **Describe the Fluid Composition:**
- The fluid in the hemocoel is composed of **plasma** and **hemocytes**. Plasma is the liquid component of blood, while hemocytes are the cells present in the hemolymph that play roles in defense and other functions.

**Answer for D:** Plasma
**Answer for E:** Hemocytes

### Final Answers:
- A: Open
- B: Poorly developed
- C: Hemocoel
- D: Plasma
- E: Hemocytes